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Cooker hood vs opening a window: which works better?

Cooker hoods work to rid your kitchen of smells, steam and airborne grease, but won’t opening a window do exactly the same thing, without using any energy?
Cooker hood

Boiling pots of water, frying cooking oils, simmering a fragrant meal - all of these things release particles into the air in your kitchen which linger and settle if not extracted. 

If your kitchen isn't ventilated, you'll soon find it damagingly humid, with sticky grease deposits on top of your cupboards and appliances.

This is where cooker hoods come in. They sit above your hob and suck up the airborne by-products of your cooking, either releasing them outside or filtering them out and recirculating clean air back into your kitchen. 

But are they an unnecessary expense? Read on for our advice on whether you really need a cooker hood, plus running costs and reviews of the latest models we've tested.

Read our guide to the best cooker hoods to find a model the right size, style and quality for your kitchen.

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Do you really need a cooker hood?

Many home cooks simply fling open their windows to ventilate their kitchens. This is especially appealing in the heat of summer when turning on an extractor fan seems a waste of energy.

Generally speaking, a cooker hood will always do a much better job than an open window, but it depends on the circumstances. 

WindowCooker hood
Tend to be positioned away and to the side of your hob, the source of steam and grease.Placed directly above the source of steam and grease, meaning the hot air will naturally rise and funnel into it.
Releases steam as air travels from hot kitchen to colder exterior, but as the temperature of your kitchen starts to match the outdoors, this effect slows and the humidity creates condensation on your surfaces.Vigorously pulls air into it and through its built-in filters for as long as you have it on.  
Can cause your home’s temperature to plummet when opened in winter.Extracts outwards and prevents draughts coming in, improving your home’s efficiency by trading off a small operating bill against the bigger one of heating your home.

As our table shows, there are good reasons to invest in a cooker hood. And the initial outlay is a lot more bearable when you measure the costs of water damage in your kitchen as well as the unpleasant effects of airborne oil hanging around.

Two-in-one venting hobs are equipped with downdraft extractors to ventilate while you cook. Read more about the best venting hobs.

Cooker hood power ratings

Cooker hood manufacturers publish the power ratings of cooker hoods. This is measured in cubic metres per hour (m3/h). The higher the number, the more air your cooker hood will extract in an hour. 

For example, we've just tested the Neff N70 D95BMP5N0B which claims to extract 437 cubic metres per hour - though we actually measured this at 439 cubic metres per hour.

For the most polluting cooking tasks, like frying, searing and boiling, you'll want to completely exchange the air in your kitchen several times over the course of an hour.

  • For a small kitchen, as low as 200m3/h can be sufficient. 
  • For a medium-to-large kitchen, you'll want a cooker hood that extracts approximately 400m3/h.

Simply opening a window won't facilitate a complete exchange of all the air in your kitchen several times over an hour but a decent cooker hood should guarantee this level of extraction. 

Find out how to stop condensation to keep your home free of expensive damage.

How much do cooker hoods cost to run?

Cooker hood sucking up steam

With energy costs spiraling, you might wonder whether running a cooker hood is an efficient use of energy.

A cooker hood won't be the worst energy guzzler in your kitchen by a long shot. Depending on the extraction rate, something that you'll want to vary depending on the size of your kitchen and the size of your hob, you're looking at between 50 to 300 watts of energy used per hour.

The issue comes in the fact that cooker hoods are often run for a long time. As a baseline, we're considering one hour of use per day as representative of average use. 

Our latest tests of 12 cooker hoods showed that, on average and according to the current electricity price cap for direct debit customers, it cost four pence to run a cooker hood for a full hour. 

  • The most expensive cooker hood, a powerful 90cm-wide model, cost seven pence an hour to run.
  • The cheapest cooker hood, fit for small kitchens, cost just two pence per hour to run.

If you compare this against the cost of cleaning mould, mildew and accumulated grease from your kitchen, or the cost of reheating your home after losing heat through an open window, it's not bad value at all. 

How to save money when running a cooker hood

To help you save money, it's best to only turn on the cooker hood when your cooking starts to evaporate water and oil.

Most cooker hoods have a 'boost mode' which makes extraction more vigorous for a short period of time, usually 15 minutes.

Boost mode uses more wattage, but if you can switch off your cooker hood after 15 minutes rather than 30, it's likely you'll save some energy overall. 

Go to Which kitchen appliances use the most energy? to see the average running cost for the most common appliances, and get tips on saving energy.

Recently tested cooker hoods

We've recently tested a new batch of cooker hoods. Among these are one of the best cooker hoods we've tested, a top-scoring Best Buy.

But some of these are also disappointing, showing a limited ability to extract steam and grease. They also have some other annoyances like hard-to-remove filters and a tendency to be too loud. 

59cm wide

60cm wide

88cm wide

90cm wide

We've tested over one hundred cooker hoods in our lab. Which? members can read our cooker hood reviews to see the best and the worst.